diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/flate/fast_encoder.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/flate/fast_encoder.go | 193 |
1 files changed, 0 insertions, 193 deletions
diff --git a/vendor/github.com/klauspost/compress/flate/fast_encoder.go b/vendor/github.com/klauspost/compress/flate/fast_encoder.go deleted file mode 100644 index c8124b5c4..000000000 --- a/vendor/github.com/klauspost/compress/flate/fast_encoder.go +++ /dev/null @@ -1,193 +0,0 @@ -// Copyright 2011 The Snappy-Go Authors. All rights reserved. -// Modified for deflate by Klaus Post (c) 2015. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package flate - -import ( - "encoding/binary" - "fmt" -) - -type fastEnc interface { - Encode(dst *tokens, src []byte) - Reset() -} - -func newFastEnc(level int) fastEnc { - switch level { - case 1: - return &fastEncL1{fastGen: fastGen{cur: maxStoreBlockSize}} - case 2: - return &fastEncL2{fastGen: fastGen{cur: maxStoreBlockSize}} - case 3: - return &fastEncL3{fastGen: fastGen{cur: maxStoreBlockSize}} - case 4: - return &fastEncL4{fastGen: fastGen{cur: maxStoreBlockSize}} - case 5: - return &fastEncL5{fastGen: fastGen{cur: maxStoreBlockSize}} - case 6: - return &fastEncL6{fastGen: fastGen{cur: maxStoreBlockSize}} - default: - panic("invalid level specified") - } -} - -const ( - tableBits = 15 // Bits used in the table - tableSize = 1 << tableBits // Size of the table - tableShift = 32 - tableBits // Right-shift to get the tableBits most significant bits of a uint32. - baseMatchOffset = 1 // The smallest match offset - baseMatchLength = 3 // The smallest match length per the RFC section 3.2.5 - maxMatchOffset = 1 << 15 // The largest match offset - - bTableBits = 17 // Bits used in the big tables - bTableSize = 1 << bTableBits // Size of the table - allocHistory = maxStoreBlockSize * 5 // Size to preallocate for history. - bufferReset = (1 << 31) - allocHistory - maxStoreBlockSize - 1 // Reset the buffer offset when reaching this. -) - -const ( - prime3bytes = 506832829 - prime4bytes = 2654435761 - prime5bytes = 889523592379 - prime6bytes = 227718039650203 - prime7bytes = 58295818150454627 - prime8bytes = 0xcf1bbcdcb7a56463 -) - -func load3232(b []byte, i int32) uint32 { - return binary.LittleEndian.Uint32(b[i:]) -} - -func load6432(b []byte, i int32) uint64 { - return binary.LittleEndian.Uint64(b[i:]) -} - -type tableEntry struct { - offset int32 -} - -// fastGen maintains the table for matches, -// and the previous byte block for level 2. -// This is the generic implementation. -type fastGen struct { - hist []byte - cur int32 -} - -func (e *fastGen) addBlock(src []byte) int32 { - // check if we have space already - if len(e.hist)+len(src) > cap(e.hist) { - if cap(e.hist) == 0 { - e.hist = make([]byte, 0, allocHistory) - } else { - if cap(e.hist) < maxMatchOffset*2 { - panic("unexpected buffer size") - } - // Move down - offset := int32(len(e.hist)) - maxMatchOffset - // copy(e.hist[0:maxMatchOffset], e.hist[offset:]) - *(*[maxMatchOffset]byte)(e.hist) = *(*[maxMatchOffset]byte)(e.hist[offset:]) - e.cur += offset - e.hist = e.hist[:maxMatchOffset] - } - } - s := int32(len(e.hist)) - e.hist = append(e.hist, src...) - return s -} - -type tableEntryPrev struct { - Cur tableEntry - Prev tableEntry -} - -// hash7 returns the hash of the lowest 7 bytes of u to fit in a hash table with h bits. -// Preferably h should be a constant and should always be <64. -func hash7(u uint64, h uint8) uint32 { - return uint32(((u << (64 - 56)) * prime7bytes) >> ((64 - h) & reg8SizeMask64)) -} - -// hashLen returns a hash of the lowest mls bytes of with length output bits. -// mls must be >=3 and <=8. Any other value will return hash for 4 bytes. -// length should always be < 32. -// Preferably length and mls should be a constant for inlining. -func hashLen(u uint64, length, mls uint8) uint32 { - switch mls { - case 3: - return (uint32(u<<8) * prime3bytes) >> (32 - length) - case 5: - return uint32(((u << (64 - 40)) * prime5bytes) >> (64 - length)) - case 6: - return uint32(((u << (64 - 48)) * prime6bytes) >> (64 - length)) - case 7: - return uint32(((u << (64 - 56)) * prime7bytes) >> (64 - length)) - case 8: - return uint32((u * prime8bytes) >> (64 - length)) - default: - return (uint32(u) * prime4bytes) >> (32 - length) - } -} - -// matchlen will return the match length between offsets and t in src. -// The maximum length returned is maxMatchLength - 4. -// It is assumed that s > t, that t >=0 and s < len(src). -func (e *fastGen) matchlen(s, t int32, src []byte) int32 { - if debugDecode { - if t >= s { - panic(fmt.Sprint("t >=s:", t, s)) - } - if int(s) >= len(src) { - panic(fmt.Sprint("s >= len(src):", s, len(src))) - } - if t < 0 { - panic(fmt.Sprint("t < 0:", t)) - } - if s-t > maxMatchOffset { - panic(fmt.Sprint(s, "-", t, "(", s-t, ") > maxMatchLength (", maxMatchOffset, ")")) - } - } - s1 := int(s) + maxMatchLength - 4 - if s1 > len(src) { - s1 = len(src) - } - - // Extend the match to be as long as possible. - return int32(matchLen(src[s:s1], src[t:])) -} - -// matchlenLong will return the match length between offsets and t in src. -// It is assumed that s > t, that t >=0 and s < len(src). -func (e *fastGen) matchlenLong(s, t int32, src []byte) int32 { - if debugDeflate { - if t >= s { - panic(fmt.Sprint("t >=s:", t, s)) - } - if int(s) >= len(src) { - panic(fmt.Sprint("s >= len(src):", s, len(src))) - } - if t < 0 { - panic(fmt.Sprint("t < 0:", t)) - } - if s-t > maxMatchOffset { - panic(fmt.Sprint(s, "-", t, "(", s-t, ") > maxMatchLength (", maxMatchOffset, ")")) - } - } - // Extend the match to be as long as possible. - return int32(matchLen(src[s:], src[t:])) -} - -// Reset the encoding table. -func (e *fastGen) Reset() { - if cap(e.hist) < allocHistory { - e.hist = make([]byte, 0, allocHistory) - } - // We offset current position so everything will be out of reach. - // If we are above the buffer reset it will be cleared anyway since len(hist) == 0. - if e.cur <= bufferReset { - e.cur += maxMatchOffset + int32(len(e.hist)) - } - e.hist = e.hist[:0] -} |